PSI - Issue 64

Ali Saeedi et al. / Procedia Structural Integrity 64 (2024) 2044–2050 Ali Saeedi/ Structural Integrity Procedia 00 (2019) 000 – 000

2047

4

Fig. 2. Time-temperature diagram obtained from simulation and experiments for the Fe-SMA reinforcement

3.2. Effect of activation voltage For a fixed shape and dimensions of the reinforcement, the activation voltage primarily influences the temperature distribution. In all cases, the voltage was applied on the SMA and then turned off after a duration of 5 seconds. The geometrical conditions for the beam was similar to the beam in section 3.1. The temperature behavior in Fe-SMA upon activation is depicted in Fig. 3.

Fig. 3. Time-temperature diagram for the Fe-SMA strip (left) and bar (right)

The temperature distribution across the bar specimen under varying activation voltages is illustrated in Fig. 4. These results are recorded after 30 seconds of activation. The results clearly demonstrate that with constant electrical resistance in the Fe-SMA, increasing the activation voltage leads to a significant rise in temperature within the SMA reinforcement. It is important to calculate the appropriate activation voltage for each reinforcement configuration to avoid overheating the structure. Conversely, a lower voltage might not fully activate the shape memory alloy. For instance, with a bar reinforcement of 2.67 mm diameter, an activation voltage of 8V fails to achieve full activation. Increasing the voltage to 12V can elevate the temperature to over 250°C in less than 8 seconds. Similar behavior can also be seen for the activation of strip, with lower temperature range.